:root {
  --bg: #f7f8fb;
  --surface: #ffffff;
  --text: #16181d;
  --muted: #5d6475;
  --border: #e3e6ee;
  --accent: #2f7cf6;
  --accent-text: #ffffff;
  --accent-soft: #e8f0fe;
  --good: #1f9d55;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 4px 16px rgba(16, 24, 40, .06);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #171a21;
    --text: #e8eaf0;
    --muted: #9aa3b5;
    --border: #262b36;
    --accent: #5b9bff;
    --accent-text: #0b1020;
    --accent-soft: #1b2638;
    --good: #46c27a;
    --shadow: none;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "Apple SD Gothic Neo", "Noto Sans KR", Roboto, sans-serif;
}
body:lang(ja) { font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic UI", Meiryo, "Noto Sans JP", sans-serif; }
body:lang(zh) { font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif; }
.langs .menu a:lang(ja) { font-family: "Hiragino Sans", "Yu Gothic UI", Meiryo, "Noto Sans JP", sans-serif; }
.langs .menu a:lang(zh) { font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .92em;
  background: var(--accent-soft); padding: .1em .35em; border-radius: 4px; }
.wrap { max-width: 1040px; margin: 0 auto; padding: 0 16px; }

/* header */
.top { position: sticky; top: 0; z-index: 10; background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px); border-bottom: 1px solid var(--border); }
.top .wrap { display: flex; align-items: center; gap: 16px; height: 60px; }
.logo { font-weight: 800; font-size: 20px; color: var(--text); letter-spacing: -.02em; }
.logo:hover { text-decoration: none; }
.logo span { color: var(--accent); }
nav { display: flex; gap: 14px; margin-left: auto; align-items: center; flex-wrap: wrap; }
nav a { color: var(--muted); font-size: 15px; }
nav a.active, nav a:hover { color: var(--text); text-decoration: none; }
.who { font-size: 14px; color: var(--muted); }
.langs { position: relative; font-size: 15px; }
.langs summary { list-style: none; cursor: pointer; color: var(--muted); }
.langs summary::-webkit-details-marker { display: none; }
.langs[open] summary, .langs summary:hover { color: var(--text); }
.langs .menu { position: absolute; right: 0; top: calc(100% + 8px); display: grid; min-width: 150px; padding: 6px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 12px; box-shadow: var(--shadow); z-index: 20; }
.langs .menu a { padding: 8px 10px; border-radius: 8px; color: var(--text); white-space: nowrap; }
.langs .menu a:hover, .langs .menu a.active { background: var(--accent-soft); text-decoration: none; }

/* buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 44px; padding: 0 18px;
  border-radius: 10px; font-weight: 600; font-size: 15px; border: 1px solid transparent; cursor: pointer; }
.btn:hover { text-decoration: none; filter: brightness(1.05); }
.btn.primary { background: var(--accent); color: var(--accent-text); }
.btn.ghost { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn[disabled] { opacity: .55; cursor: default; }

/* hero */
.hero { padding: 72px 0 48px; text-align: center; }
.hero h1 { font-size: clamp(30px, 6vw, 48px); line-height: 1.15; margin: 0 0 16px; letter-spacing: -.03em; }
.hero p { color: var(--muted); font-size: 18px; max-width: 640px; margin: 0 auto 28px; }
.actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* sections */
section { padding: 40px 0; }
h2 { font-size: 28px; letter-spacing: -.02em; margin: 0 0 8px; }
.lead { color: var(--muted); margin: 0 0 28px; }
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr)); }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 14px; padding: 20px; box-shadow: var(--shadow); }
.card h3 { margin: 0 0 6px; font-size: 17px; }
.card p { margin: 0; color: var(--muted); font-size: 15px; }
.icon { font-size: 24px; display: block; margin-bottom: 8px; }
.steps { counter-reset: step; display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr)); }
.steps .card::before { counter-increment: step; content: counter(step); display: inline-grid; place-items: center;
  width: 28px; height: 28px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font-weight: 700; margin-bottom: 8px; }

/* commands */
table { width: 100%; border-collapse: collapse; background: var(--surface); border: 1px solid var(--border); border-radius: 14px; overflow: hidden; }
th, td { text-align: left; padding: 12px 16px; border-bottom: 1px solid var(--border); vertical-align: top; }
tr:last-child td { border-bottom: 0; }
th { font-size: 13px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
td:first-child { white-space: nowrap; }
.table-wrap { overflow-x: auto; }

/* pricing */
.plans { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr)); align-items: stretch; }
.plan { display: flex; flex-direction: column; gap: 12px; }
.plan.featured { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent), var(--shadow); }
.plan .price { font-size: 32px; font-weight: 800; letter-spacing: -.02em; }
.plan .price small { font-size: 15px; font-weight: 500; color: var(--muted); }
.plan ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 6px; font-size: 15px; }
.plan li::before { content: "✓ "; color: var(--good); font-weight: 700; }
.plan .alt { font-size: 14px; color: var(--muted); }
.plan .spacer { flex: 1; }
.badge { display: inline-block; font-size: 12px; font-weight: 700; padding: 2px 8px; border-radius: 999px; background: var(--accent-soft); color: var(--accent); }
.notice { background: var(--accent-soft); border-radius: 12px; padding: 14px 16px; font-size: 15px; }
.error { color: #d93025; font-size: 14px; min-height: 1.2em; }
.plan .btn + .btn { margin-top: -4px; }

/* USDT payment */
.btn.small { min-height: 30px; padding: 0 10px; font-size: 13px; border-radius: 8px; }
.pay-amount { display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 10px 14px; margin: 18px 0 6px; }
.pay-amount strong { font-size: 30px; font-weight: 800; letter-spacing: -.01em; }
.networks { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 320px), 1fr)); margin: 20px 0; text-align: left; }
.network { display: flex; flex-direction: column; gap: 10px; }
.network h3 { margin: 0; }
.network .qr { align-self: center; line-height: 0; }
.network .qr svg { width: 180px; height: 180px; border-radius: 8px; }
.network dl { margin: 0; display: grid; gap: 4px; }
.network dt { font-size: 13px; color: var(--muted); }
.network dd { margin: 0 0 6px; display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.network dd code { word-break: break-all; }
.network .hint { font-size: 14px; color: var(--muted); margin: 0; }

/* prose (legal) */
.prose { max-width: 760px; }
.prose h1 { font-size: 32px; letter-spacing: -.02em; }
.prose h2 { font-size: 20px; margin-top: 28px; }
.prose p, .prose li { color: var(--text); }

footer { border-top: 1px solid var(--border); margin-top: 48px; padding: 24px 0 40px; color: var(--muted); font-size: 14px; }
footer .wrap { display: flex; gap: 16px; flex-wrap: wrap; justify-content: space-between; }
footer nav { margin: 0; }

@media (max-width: 640px) {
  .top .wrap { height: auto; padding-top: 10px; padding-bottom: 10px; flex-wrap: wrap; }
  nav { margin-left: 0; width: 100%; gap: 12px; }
  .hero { padding: 48px 0 32px; }
}